International patent application publication No.98/41304 discloses such a well having a horizontal section that includes the separation chamber.
U.S. Pat. No. 5,842,520 and U.S. Pat. No. 5,979,559 discloses such a well, wherein the separation chamber is located at substantially the same level as the production formation.
International patent application publication No.98/02637 discloses such a well, wherein the separation chamber is located at the level of the production formation, and wherein the static separator is a cyclone separator.
U.S. Pat. No. 4,793,408 discloses such a well, wherein the separation chamber is a small-diameter chamber located within a section of the well and having a side inlet for the well fluid, and wherein the separation chamber is provided with regulators for regulating the discontinuous withdrawal of effluents.
U.S. Pat. No. 5,443,120 discloses a cased well including a separation section in the casing adjacent the underground production formation, which is arranged for separating of at least a portion of the water from the well fluid.
U.S. Pat. No. 5,857,519 discloses a gas lift well including a separator arranged in the annulus between the casing and a tubing string and adjacent the underground production formation.
The known systems generally suffer from one or more drawbacks, including an insufficient degree of separation, complexity and high installation cost, limited robustness, limited operation window for oil production flow rates and watercut.